The present invention relates to a coupling for axially connecting a drive shaft with a driven shaft, and more particularly relates to such a coupling of the quick release type for connecting a driven cardanshaft of a piece of agricultural equipment and an output shaft of a farm tractor. The coupling of the present invention is of the type including a coupling sleeve with a ball-catch mechanism to provide locking engagement between the cardanshaft and the drive shaft, and a release lever mounted on a coupling box surrounding the drive shaft for engaging and releasing the ball-catch mechanism to allow easy disconnect between the drive shaft and the driven cardanshaft.
Quick release couplings in which a cardanshaft is directly coupled to a power output shaft of a tractor are known, such as shown in German PS Pat. No. 1 600 225. In this earlier arrangement, a frustoconical member having externally carried teeth is fitted onto the output shaft and is secured thereon by an elastic pin having a spherical head which is adapted to engage with an annular groove on the output shaft. A mating conical sleeve having internal teeth is then pushed over the frustoconical member and secured by claw or clutch elements.
The drawback of this type of conventional arrangement is that the connection between the frustoconical member and the output shaft is not a positive one and is purely dynamic. It has been found that this type of connection is insufficient in that the frustoconical member frequently falls or jumps off the end of the output shaft.
Another prior proposal is shown in German PS Pat. No. 2 537 601 which has a coupling hub fitted onto the power output shaft and is secured thereon by a ball-catch mechanism. A coupling sleeve is then pushed over the hub and is also secured on the shaft by a ball-catch mechanism. Both of the ball-catch mechanisms are radially maintained in operatively locking position by a securing ring to provide a form fitting positive connection between the various members. This is an improvement over the prior coupling mechanism in that the coupling cannot be accidentally disengaged, however, this device is relatively complicated and expensive. In addition, tools are required to disengage the coupling hub from the output shaft.
It is accordingly a principal object of the present invention to provide a quick release coupling which can fit directly onto an end of the drive shaft and be securely held thereon by a positive form fitting connection. It is also an object of the invention to provide means for quickly releasing the coupling without the use of tools by providing a release lever which can be operated from the outside of the coupling.
Other objects, features and advantages of the present invention will become more apparent from the description of the invention in connection with the accompanying drawings to be described more fully hereinafter.